Typically, nonionic synthetic detergents having the desired detergency properties for incorporation into commercial granular detergent products, such as laundry powders, are thick, viscous, sticky liquids or semi-solid or waxy materials. The presence of these materials in a detergent slurry (crutcher mix) prior to spray drying in amounts greater than about 2-5 percent by weight is impractical since the nonionic synthetic detergent will "plume" during psray drying and a significant portion can be lost through the gaseous exhaust of the spray drying tower.
The art has recognized the application of nonionic synthetic detergents of this type to various particulate carrier bases to produce relatively free flowing granular products that can be used as household laundry products. Representative patents containing teachings and disclosures of methods for producing granular free flowing laundry detergents by post spraying a nonionic synthetic organic detergent onto a spray dried particulate product containing detergent builders include; among others: Di Salvo et al U.S. Pat. Nos. 3,849,327 and 3,888,098; Gabler et al U.S. Pat. No. 3,538,004; Kingry U.S. Pat. No. 3,888,781; and British Patent No. 918,499 (Feb. 13, 1963). The prior art in this regard is typified by post spraying from about 1 to a maximum of 10 percent by weight of a nonionic synthetic detergent onto a spray dried bead that contains a substantial proportion of a surface active agent such as anionic detergents, filler materials, and detergent builders.
Further, certain desirable ingredients for detergent formulations such as cationic surface active agents that provide fabric softening properties and optical brighteners, bluing agents and enzymatic materials cannot be spray dried because of thermal decomposition. Such materials can be incorporated into a granular detergent according to the invention by post spraying them onto the spray dried base builder beads either alone or in addition to a nonionic detergent or other suitable ingredients.